1. Field of the Invention
The present invention relates to a washing machine and a water level control method thereof, and, more particularly, to a washing machine and a water level control method thereof that can supply an appropriate amount of water based on the amount of laundry.
2. Description of the Related Art
Generally, a washing machine (normally, a drum-type washing machine) is a machine in which, when a cylindrical rotary drum is rotated, laundry and wash water in the rotary drum are raised along the inner surface of the rotary drum and fall, whereby washing of the laundry is accomplished. The washing machine includes a water tub to receive water (wash water or rinse water) and a rotary drum rotatably mounted in the water tub. The rotary drum has a plurality of holes (through-holes) formed at the entire circumference thereof such that, when water is supplied into the water tub for washing, the water filling the water tub flows to the laundry in the rotary drum through the holes of the rotary drum.
In the conventional washing machine with the rotary drum having the holes, however, when water (wash water or rinse water) is supplied into the water tub, it is necessary to supply water to the extent that a space between the inner surface of the water tub and the outer surface of the rotary drum and laundry in the rotary drum are submerged in the water. As a result, the consumption of water is excessive.
In order to solve this problem, there has been developed a washing machine with a rotary drum having no holes formed at the circumference thereof (a holeless washing machine), an example of which is disclosed in Korean Unexamined Patent Publication No. 2005-11515.
According to the disclosure, no holes are formed at the circumference of the rotary drum, and an additional water circulation unit is provided to supply water into the rotary drum. After water (wash water or rinse water) is supplied into the water tub, the water received in the water tub is introduced into the rotary drum through the circulation unit, whereby the consumption of water is reduced.
In the washing machine with the holeless rotary drum, the water is introduced into the rotary drum through the circulation of the water. Since no holes are formed at the circumference of the rotary drum, however, the remaining water, which has not been absorbed into the laundry, is not discharged out of the rotary drum. As a result, it is not possible to confirm whether an appropriate amount of water has been supplied based on the amount of the laundry.
When water supplied into the water tub is absorbed into the laundry through the holes formed at the circumference of the rotary drum, and the water level is changed depending upon the amount of water absorbed by the laundry, a water level sensor is used to control additional supply of water based on the changed water level data, thereby supplying the optimum amount of water based on the amount of the laundry. However, the washing machine with the holeless rotary drum cannot adopt the water level sensor.